1. Field of the Invention
The present invention relates generally to a gas turbine engine, and more specifically to a strip seal between adjacent shroud segments of the turbine.
2. Description of the Related Art including information disclosed under 37 CFR 1.97 and 1.98
In a gas turbine engine, a compressed air from a compressor is burned with a fuel in a combustor to produce a hot gas flow. The hot gas flow is passed through a multiple stage turbine to convert most of the energy from the gas flow into mechanical work to drive the compressor, and in the case of an aero engine to drive a fan, and in the case of an industrial gas turbine (IGT) engine to drive an electric generator to produce electrical power.
The turbine section of the engine is exposed to the high temperature gas flow. A plurality of stages of rotor blades and stator vanes react with the hot gas flow to convert the energy from the gas flow into mechanical energy to drive the rotor shaft. Stator vanes are formed with end walls or platforms on the inner and the outer diameters with the airfoil extending between the end walls to form a flow path through adjacent vanes for the hot gas stream or flow in the turbine. The stator vanes are formed of one, two or sometimes three vanes per segment in which several segments are placed around the turbine to form a complete annular vane stage. Adjacent vanes require a seal placed within grooves on the end wall faces to form a seal in the space between adjacent vane end walls. The space will be large during the turbine cold condition and decrease as the engine heats up during startup until a steady state is reached.
Gas turbine engines use strip seals between adjacent static components such as ring segments, casing components and stator vanes. Strip seals are long, ruler like seals that fit into aligned slots in each adjacent component. FIG. 1 shows this prior art strip seal. The seal must be smaller than the slot to enable assembly of the components and allow for machining variations such as seal slot misalignment and undersized slots. In the absence of a high pressure gradient to load the seal, the failure to positively engage the components results in increased seal wear due to engine vibration or aero flutter or increase leakage flow across the seal.